Wireless local access network system detection and selection

ABSTRACT

Method and apparatus for detection and selection of Wireless Local Area Network (WLAN) service. A cellular network may provide an advertisement for a WLAN, such as in an overhead signaling message. The advertisement may identify the Access Point(s) by an Extended Service Set Identifier (ESSID). The remote station may then scan for the WLAN service automatically or manually.

CLAIM OF PRIORITY UNDER ±U.S.C. §120

The present Application for Patent is a Continuation and claims priorityto patent application Ser. No. 10/373,346 entitled “Wireless LocalAccess Network System Detection and Selection” filed Feb. 24, 2003, nowallowed, and assigned to the assignee hereof and hereby expresslyincorporated by reference herein.

REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT

The present Application for Patent is related to the followingco-pending U.S. patent applications: “WIRELESS LOCAL ACCESS NETWORKSYSTEM DETECTION AND SELECTION” by Raymond T. Hsu et al., having patentapplication Ser. No. 10/374,810, filed Feb. 24, 2003, assigned to theassignee hereof, and expressly incorporated by reference herein; and

“WIRELESS LOCAL ACCESS NETWORK SYSTEM DETECTION AND SELECTION” havingpatent application Ser. No. 10/373,557, filed Feb. 24, 2003, assigned tothe assignee hereof, and expressly incorporated by reference herein.

BACKGROUND

1. Field

The present invention relates generally to communication systems, andmore specifically to detection of a Wireless Local Access Network (WLAN)by a mobile station in a cellular communication system.

2. Background

Wireless Local Access Networks (WLANs) provide wireless access to acommunication network within a local geographical area, such as abuilding or in a cybercafe. WLANs are currently considered by manycellular carriers to alleviate loading of a cellular system, so as toincrease capacity. Additionally, users desire access to local WLANs toenhance reception and data rates of communications through a wirelessdevice. A problem exists in detecting and selecting WLAN systems. Thepurpose of system detection is to detect the availability of a wirelessaccess medium (e.g., cdma2000, WLAN, etc.). The purpose of systemselection is to select an access medium for transporting applicationcontents. System selection may be based on the availability of accessmedia, preference policy, application status, user intervention, etc.,or a combination thereof.

Typically, a cellular system transmits a paging indicator periodicallyto page a mobile station when there is a pending communication.Similarly, a WLAN may be advertised by a beacon transmitted by the WLAN.Both the paging indicator and the beacon require the mobile station toscan for the transmitted signal. As the mobile station often has littleinformation as to the location and accessibility of a WLAN, the mobilestation may scan for the WLAN periodically expending considerable power.There is a need therefore for an efficient, accurate method of systemdetection and selection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a mobile station adapted for system detection and selection.

FIG. 2A is a communication configuration including cellular systemcapability and WLAN access.

FIG. 2B illustrate signaling messages for advertising WLAN.

FIG. 3A is a timing diagram of signal flow in a system as in FIG. 2A.

FIG. 3B is a timing diagram of signal flow in a system as in FIG. 2A.

FIG. 4 is a timing diagram of signal flow in a system as in FIG. 2A.

FIG. 5A is a mobile station having a display format associated with WLANdetection.

FIG. 5B is a flow diagram of a method for system detection andselection.

FIG. 6 is a block diagram of a mobile station with multiple tuners incommunication with a WLAN and a cellular system.

FIG. 7 is a flow diagram of a method for system detection.

FIG. 8 is a communication system supporting wireless cellularcommunications, wireless local area network communications, and Internetcommunications.

FIG. 9 is a timing diagram illustrating WLAN detection and selection.

FIG. 10A is a timing diagram illustrating WLAN detection and selection.

FIG. 10B is a timing diagram illustrating WLAN detection and selection.

FIG. 10C is a timing diagram illustrating WLAN detection and selection.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

An HDR subscriber station, referred to herein as an access terminal(AT), may be mobile or stationary, and may communicate with one or moreHDR base stations, referred to herein as modem pool transceivers (MPTs).An access terminal transmits and receives data packets through one ormore modem pool transceivers to an HDR base station controller, referredto herein as a modem pool controller (MPC). Modem pool transceivers andmodem pool controllers are parts of a network called an access network.An access network transports data packets between multiple accessterminals. The access network may be further connected to additionalnetworks outside the access network, such as a corporate intranet or theInternet, and may transport data packets between each access terminaland such outside networks. An access terminal that has established anactive traffic channel connection with one or more modem pooltransceivers is called an active access terminal, and is said to be in atraffic state. An access terminal that is in the process of establishingan active traffic channel connection with one or more modem pooltransceivers is said to be in a connection setup state. An accessterminal may be any data device that communicates through a wirelesschannel or through a wired channel, for example using fiber optic orcoaxial cables. An access terminal may further be any of a number oftypes of devices including but not limited to PC card, compact flash,external or internal modem, or wireless or wireline phone. Thecommunication link through which the access terminal sends signals tothe modem pool transceiver is called a reverse link. The communicationlink through which a modem pool transceiver sends signals to an accessterminal is called a forward link.

FIG. 1 illustrates the components and interfaces for the systemdetection and selection according to one embodiment. Within system 50, auser 52 represents a user of a wireless mobile unit, wherein the user 52is a human capable of manually selecting an access medium orimplementing an automatic selection process. An application 54 is acomputer-readable program or protocol stack (e.g., Transmission ControlProtocol (TCP)/Internet Protocol (IP) stack) requiring an access mediumfor transport. The application 54 communicates with the user 52 viainterface C. The application 54 also communicates with a preferencedatabase 56 via interface B, and with a selector 58 via interface E.

The preference database 56 is a memory device storing a system selectioncriteria. The system selection criteria may be configured manually bythe user 52 or manipulated automatically by the application 54. In oneembodiment, the system selection criterion considers the availability ofwireless access and selects WLAN when available. In one example, if thesystem 50 is currently communicating via the cellular network, such as acdma2000 network, the system 50 is instructed to continue suchcommunication but to continue to try to detect the availability of WLAN.The application 54 may configure the preference database 56automatically. The user 52 may manually configure the preferencedatabase 56 and enable/disable the application 54.

An Access Medium Detector (AMD) 60 detects the availability of awireless access medium and reports the results to the selector 58. Theselector 58 is responsible for enabling or disabling one or more AccessMedium Detectors 60 and selecting an access medium based on thedetection results, system selection criteria, application status, and/oruser request. The Selector 60 may inform the system selection result tothe user 52 and/or application 54. The selector 60 communicates withapplication 54 via interface E, with preference database 56 viainterface F, and with AMDs 60 via interface G. The selector 58 furthercommunicates with user 52 via interface D.

Interface A: The user 52 may manually load new system selection criteriaor modify existing system selection criteria in the preference database56. System selection criteria are rules that the selector 58 will usefor decision making. For example, if an application is active (i.e.,sending/receiving data) and the WLAN access medium is available, thenthe system should select the WLAN access medium to transport datatraffic. The user may input system selection criteria via a user-graphicinterface (e.g., window-based programs).

Interface B: The application 54 may automatically load new systemselection criteria or modify existing system selection criteria in thepreference database 56. For example, an application 54 having apreference to use a given access medium X, and the preference may beloaded in the preference database 56 automatically when the application54 is downloaded or installed.

Interface C: The user 52 may enable or disable the application 54. Theuser 52 may configure the application 54 setting for system selection.For example, the user 52 may configure the application 54 to prohibitautomatic interaction with the preference database 56, such as when theuser 52 decides to manually control the application 54 level preferencevia Interface A.

Interface D: The selector 58 may prompt the user to select an accessmedium. In another scenario, without such prompt the user 52 may requesta specific access medium, wherein such request overrides other systemselection criteria.

Interface E: The application 54 may provide status information tofacilitate the selector 58 in system selection. For example, whether theapplication 54 is enabled or disabled influences the Selector 58decision to enable or disable the Access Medium Detector 60. TheSelector 58 may provide the system selection result to the application54, based on the indication from the access medium detector(s) andsystem selection criteria stored in the preference database. Forexample, if the Selector 58 selects an access medium with higherbandwidth, the application 54 may switch to a codec with better quality.In another example, the Selector 58 relays the system detection resultsto the application 54 from an Access Medium Detector 60, so that theapplication 54 may display the results to the user 52.

Interface F: The Selector 58 obtains the system selection criteria fromthe preference database 56. If there is a change in the system selectioncriteria (e.g., modified by the user 52), the Selector 58 must fetch thenew criteria from the preference database 56. The Selector identifies achange in the criteria by a variety of methods, such as: (1) The user 52(or Application 54) provides information to the Selector 58 via the D(or E) Interface indicating a preference database 56 update, or (2) TheSelector 58 periodically checks the preference database 56 for updates.

Interface G: The Selector 58 may enable or disable one or more AccessMedium Detectors 60 based on user input, application status, and/orsystem selection criteria from the preference database 56. The AccessMedium Detector 60 may indicate the detection result to the Selector 58.

Provisioning the MS with WLAN Information

The following discussion details provisioning of the WLAN information inthe Mobile Station (MS) and methods implemented at the MS to minimizeunnecessary WLAN scanning based on WLAN advertisement from the cellularnetwork via signaling messages. A network supporting cdma2000 protocolsis provided as an example in the following discussion. In the context ofthe present description, provisioning refers to the communication ofWLAN parameters and configuration information to the MS necessary forestablishment of communication with the WLAN.

A conventional provisioning method manually configures the MS with thenecessary information (e.g., 802.11a/b frequencies, list of serviceidentifiers, etc.) for the MS to detect WLAN coverage provided by aservice provider. Extended Service Set Identifier (ESSID) may be used toidentify all Access Points (AP) in a WLAN operator network. Differentoperators will use different ESSIDs. Thus, the list of ESSIDs maycorrespond to a list of WLAN operators accessible by the MS.

An alternative to manual provisioning is to provision the MS with theWLAN information via an Over-The-Air Provisioning (OTAP) type protocol.The detail of OTAP is described in the IS-683 standards that can beextended to support the provisioning of WLAN parameters. Anotheralternative is to automatically provision the MS with the WLANinformation advertised via 1× signaling messages (discussedhereinbelow). The latter alternative is more dynamic than OTAP.

Once the MS has the necessary WLAN information, the MS determines whento scan for WLAN coverage. Generally, the WLAN will transmit a periodicbeacon, which is a signal transmitted to advertise the WLAN. When the MSis able to receive the beacon, the MS is able to access the WLAN. Theuser 52 may enable or disable WLAN scan, however, the process may not beuser friendly, because of the manual operations required by the user. Anautomated operation may be preferred, which is transparent to the user.According to one embodiment, a scanning method transparent to the user52 provides for the MS to scan periodically. Periodic scanning isexpensive when the MS is not in WLAN coverage area as scanning drainsbattery power.

If a cellular system, such as cdma2000, also provides WLAN service orhas roaming agreement(s) with other WLAN operators, several options maybe implemented for the cellular network to advertise WLAN informationvia cellular signaling messages in order to facilitate the MS to scanfor WLAN coverage efficiently. Alternate embodiments may implement othercellular systems.

WLAN Advertisement via Signaling Messages.

In a first embodiment, a Base Station Controller (BSC) and BaseTransceiver System (BTS) are configured with the knowledge of WLANcoverage in a cell sector. When the cellular service provider alsoprovides WLAN services, the WLAN information is available to thecellular system. When there is WLAN coverage in the cell sector, the BTSperiodically broadcasts WLAN provisioning information (e.g., 802.11a/bfrequencies, ESSID, preferred roaming list, etc.) as overhead messagesvia common channels. The MS receives the WLAN provisioning informationand uses the information to scan for WLAN. The WLAN provisioninginformation may be included within existing overhead messages.Alternately, the WLAN provisioning information may be provided in asignaling message defined specifically for WLAN provisioning.

FIG. 2A illustrates sectors within a cell of a cellular communicationnetwork. The cell includes sector A 102, sector B 104, and sector C 106.Within the cell are multiple WLANS, including WLAN #1 120 and WLAN #2130. The WLAN #1 120 is identified by an ESSID(1). The WLAN #2 130 isidentified by an ESSID(2). As illustrated, the WLAN #2 130 is containedwithin sector B 104, while WLAN #1 120 includes a portion within sectorB 104 and a portion within sector A 102.

The preferred roaming list is a list of ESSIDs, each corresponding to aWLAN provider having a roaming agreement with the cellular system. Thebroadcast signaling messages may be triggered by cellular systemprovisioning, i.e., the cellular system broadcasts the message all thetime whether or not there are MSs with WLAN capability. The cellularsystem continually transmits the WLAN provisioning information so as toadvertise the WLAN. Alternately, the WLAN provisioning information maybe transmitted via signaling messages, wherein the signaling messagesare triggered on receipt of at least one registration message, andwherein the registration message indicates an MS with WLAN capability.Such WLAN capability indication may be a 1-bit flag in a registrationmessage. Note that one benefit of registration triggered signaling isthat the BTS may avoid broadcasting unnecessary WLAN provisioninginformation.

Upon receipt of the WLAN request from a MS, the BS may transmit the WLANadvertisement in a variety of ways. The BS may transmit the WLANadvertisement on a common channel, wherein multiple users are able toaccess the information. The BS may transmit the information directly tothe MS using a signaling message. The BS may transmit only specificinformation, such as location identification for the WLAN.

Upon receiving the WLAN provisioning information in an overheadsignaling message, the MS has no guarantee to detect an AP because theWLAN coverage within a cell sector may not be consistent. Theprobability of WLAN coverage increases in densely populated areas, suchas shopping centers, stadiums, etc. Cellular systems desire to increasecapacity in populated areas, and WLANs provide a means for increasingcapacity in such areas. Cellular systems, therefore, implement WLANs inpopulated areas. On the other hand, WLAN coverage is not expected inrural areas, as capacity is generally not a concern in less populatedareas.

Within cell 100, the BS (not shown) supporting sector B 104 transmits anidentifier of those WLAN for which the BS has knowledge. For example, ifthe network has relationship with the WLAN #1 120, the BS in sector B104 may transmit an advertisement of the WLAN #1 129, wherein theadvertisement provides the ESSID(1). In this way, when the MS (notshown) receives the advertisement, the MS is able to scan for the WLAN#1 129 based on the ESSID(1). Similarly, the BS of sector A 102 wouldalso be able to advertise WLAN #1 120. Additionally, if the cell networkhas a relationship with WLAN #2 130, the BS of sector B 104 may alsoadvertise for WLAN #2 130 providing ESSID(2).

FIG. 2B illustrates two embodiments of signaling messages. In a firstembodiment, the system parameter message includes system parameterinformation 112 and a WLAN advertisement field 116. The WLANadvertisement field 116 may be a single bit, wherein one polarityindicates WLAN availability and the opposite polarity indicates noavailability. The WLAN advertisement 116 may be a multiple bit fieldproviding further information, such as location information, orinstruction to the MS regarding accessing WLAN information. In a secondembodiment the system parameter message includes system parameterinformation 140, a WLAN advertisement 142, and a location information orGlobal Positioning System (GPS) 144.

In alternate embodiments, the WLAN provisioning/advertisementinformation is not broadcast periodically in overhead messages overcommon channels. When a MS wants to receive WLANprovisioning/advertisement information for a given cell sector, the MSuses a cellular signaling message, such as a cdma2000 registrationmessage to request the WLAN provisioning/advertisement information fromthe BSC. Alternately, the MS may use a specific WLAN request message. Inresponse, the BSC provides the WLAN provisioning/advertisementinformation upon demand. If the MS does not have a traffic channel, theBSC sends the reply to the MS over a common channel. The replyidentifies available WLAN coverage in the designated cell sector. Notethat the sector is identified by an identifier such as the Base_ID asused in cdma2000. When there is WLAN coverage in the sector, the replyfrom the BSC also includes the necessary WLAN provisioning/advertisementinformation so as to allow the MS to scan for WLAN coverage.

To avoid excessive signaling traffic (such as when multiple MSs requestWLAN provisioning/advertisement information), the BSC may transmit thereply (i.e., the WLAN provisioning/advertisement information) via commonchannel(s). The WLAN information may be provided redundantly. In oneembodiment, upon receipt of a request from a MS for WLANprovisioning/advertisement information, the BSC transmits the WLANprovisioning/advertisement information for a predetermined time period.The provision of such information on a common channel avoids excessivesignaling messages incurred when other MSs request the same informationat a proximate time.

The MS receives WLAN location information from the cellular network,wherein the WLAN location information identifies the APs supporting theWLAN. The location information may be latitude and longitude identifiersof an AP. The MS receives the WLAN location information and thendisplays the WLAN location information at the MS. The display mayprovide the AP location(s) in the context of a local map which may bestored in the MS. The display may be as illustrated in FIG. 5A, whereina mobile wireless device 200 includes a keypad 204 and a display 202.The display identifies the location of the WLAN APs in a graphicalmanner. The display may be a textual message.

There are several methods for the MS to obtain the location informationof APs supporting the WLAN. In one embodiment, the MS obtains thelocation information of APs from the signaling overhead messages viacommon channels or dedicated channels, as described hereinabove. In analternate embodiment, the user instructs the MS to request the locationinformation of APs from an application server. The server in this casemay reside in the backend of the operator network, so the MS useshigher-layer protocols (e.g., IP) to communicate with the server andobtain the location information of APs.

In one embodiment, illustrated in FIG. 5B, a method 250 provides amethod of manual WLAN selection. At step 252 the user selects the mapdisplay function for identifying WLAN locations on the wireless device.The WLAN is identified within range at step 254. If an automated scan isenabled at decision diamond 256, processing continues to step 258 forthe device to scan for WLANs. Else, processing continues to step 260 forthe user to scan for WLANs. If a WLAN is accessible at decision diamond262, the wireless device then sends a WLAN registration request at step264. Else, processing returns to step 254 to await a WLAN identified inrange.

FIG. 3A is a timing diagram for detection of a WLAN, wherein the MSsends a specific WLAN query or request for WLAN information to the BS.In response, the BS transmits the WLAN information to the MS, such asvia a common channel WLAN advertisement. When a WLAN is available, theMS scans for the WLAN according to the WLAN information provided by theBS and sends a registration request to the WLAN to establishcommunication.

FIG. 3B is a timing diagram for detection of a WLAN, wherein the MSsends a registration request to the BS (i.e., cellular network). Theregistration request may include a specific request for WLANinformation. Alternatively, the registration request may notspecifically request WLAN information, but rather prompts the BS toprovide WLAN information. In response to the registration request, theBS provides the WLAN information to the MS. When a WLAN is available,the MS scans for the WLAN according to the WLAN information provided bythe BS and sends a registration request to the WLAN to establishcommunication.

FIG. 4 is a timing diagram for detection of a WLAN, wherein the MS sendsa registration request to the BS (i.e., cellular network). Theregistration request may include a specific request for WLANinformation. Alternatively, the registration request may notspecifically request WLAN information, but rather prompts the BS toprovide WLAN information. In response to the registration request, theBS broadcasts the WLAN information on a common channel. When a WLAN isavailable, the MS scans for the WLAN according to the WLAN informationprovided by the BS and sends a registration request to the WLAN toestablish communication.

MS with One Tuner

When the Mobile Station (MS) has one tuner for communication. In such adevice, the single tuner is used for communication with both thecellular system and the WLAN system. The MS detects WLAN coverage andperforms system selection between WLAN and cellular system, wherein theMS may only tune to one system (WLAN or cellular) at a given time.

The MS performs system detection and selection in the followingscenarios: (1) the MS is idle (not active in communication) with respectto the cellular network, having no dedicated channel, and desires toscan for WLAN; (2) the MS has an active packet data session with thecellular network, having a dedicated channel, and desires to scan forWLAN; (3) the MS is tuned to the WLAN, and desires to receive cellularpages; and (4) the MS is tuned to the WLAN but with low signal strength.

In scenario (1) described above, if the MS is idle in the cellularnetwork (i.e., no dedicated channel), the MS may decide to scan for WLANcoverage based on one or more factors, e.g., user command,pre-configured preference, WLAN availability advertisement as receivedfrom the cellular network, etc. The MS tunes to the cellular networkduring each assigned paging slot interval. In this way, the MS is ableto receive any page indicator from the cellular network. Once the MSmonitors for cellular page indicator, the MS then is able to tune to theWLAN frequencies and use passive or active scanning to detect WLANcoverage.

In scenario (2) described above, the MS has an active packet datasession in the cellular network (i.e., with dedicated channel). The MSmay choose not to scan for WLAN while active data session in thecellular network. In this case, while the MS is active in the cellularnetwork, the MS does not switch to WLAN even though it could access toWLAN. Although the MS might not be able to take the advantage ofhigh-speed WLAN access, the MS would not experience serviceinterruption. After the MS becomes idle in the cellular network, the MStunes away from the cellular network to scan for the WLAN.

Alternatively, the cellular network may direct the MS to scan for WLANcoverage. In this case, the cellular network instructs the MS to scanfor WLAN coverage. If there is WLAN coverage, the network may direct theMS to handover its packet data session to WLAN. This procedure might beuseful when the network is overloaded or when the MS has low powerstrength. The procedure is described hereinbelow and is similar to thecandidate frequency search procedure in a system supporting cdma2000.

The MS indicates any WLAN capability to the cellular network viaover-the-air registration. If the MS is in a cell sector that has WLANhot spots, the network may send a signaling message to request the MS toscan for WLAN coverage. The signaling request message contains WLANinformation (e.g., frequencies, ESSID, etc.) and is sent over the MS'sdedicated channel. The MS tunes to WLAN frequencies and actively orpassively scans for the WLAN beacon. Then, the MS may have the followingbehaviors. (1) If the MS detects WLAN coverage, the MS tunes back to thecellular network to notify the WLAN search result. The cellular networkthen sends a signaling message to instruct the MS to handoff to WLAN.The MS tunes to WLAN and performs access authentication and optionallyMobile IP registration to handover its packet data session to WLAN. Ifaccess authentication or Mobile IP registration fails, the MS may tuneback to the cellular network and originate for packet data serviceoption.

(2) If the MS detects WLAN coverage, the MS does not return to thecellular network to notify the WLAN search result. Instead, the MSproceeds to perform WLAN access authentication and optionally Mobile IPregistration to handover its packet data session to WLAN. In this case,if the cellular network didn't receive the signaling reply message aftera timeout, the network assumes that the MS has left the cellular systemand hence removes the MS's packet data session.

(3) If the MS fails to detect WLAN coverage, the MS re-tunes to thecellular network and sends a signaling reply message to inform thecellular network about the WLAN search result, and the network restoresthe active state of the MS's packet data session.

Continuing with scenario (2) as given hereinabove, still further, the MSmay send a request to the cellular network to save the state informationof the MS while the MS tunes away to scan for WLAN coverage. In thiscase, the MS requests the cellular network to save the state informationwhile scanning for WLAN coverage. The MS sends a signaling requestmessage (similar to the CDMA Offtime Report Message) to the 1× network.If the MS is in a cell sector that has WLAN hot spots, the network maysend a signaling reply message that contains the necessary WLANinformation for the MS to scan for WLAN coverage. If the MS detects WLANcoverage and is authenticated for access, the MS may proceed with MobileIP registration to handover its packet data session via WLAN. If the MSfails to detect WLAN coverage or fails WLAN access authentication, theMS re-tunes to cellular network and sends a signaling message to requestthe cellular network to restore the active state of the MS's packet datasession. If the cellular network did not receive the signaling requestmessage after a specified timer has expired, the network assumes thatthe MS has left the cellular system and hence removes the MS's packetdata session.

According to scenario (3) the MS is currently tuned to the WLAN. If theMS is not transmitting or receiving frames over the WLAN, the MSperiodically tunes back to the cellular network and monitors the PagingIndicator on the Quick Paging Channel. If the Paging Indicator is “0,”then there is no page for the MS, and the MS immediately tunes back tothe WLAN frequency. In this case, the time the MS spent on the cellularfrequency is minimal (in the order of ms). If the Paging Indicator is“1,” then the MS monitors the Paging Channel for its paging slot. In acdma2000 type network, the Paging Indicator occurs at most 100 ms beforethe MS's paging slot. The paging slot is 80 ms. Paging Indicator of “1”does not guarantee that the page is for the MS because a second MS'sInternational Mobile Subscriber Identity (IMSI) may be hashedcoincidentally to the same Paging Indicator as the first MS. Thus, theMS may spend a maximum of 180 ms on the paging channel for nothing. Ifthe page is for the MS, it will reply with Paging Response and stay inthe cellular network to receive the incoming circuit-switched voicecall.

At the time the MS is scheduled to monitor the cellular network paging,if the MS is in the middle of transmitting or receiving frames over theWLAN, the MS should stay in the WLAN to complete the data delivery andthus skip a paging cycle. Potentially, the MS could miss a page, and thecall set-up time of an incoming circuit-switched voice call increases.If the MS receives a page for an incoming circuit-switched voice call,the MS may respond as follows.

-   -   1. Upon receiving the page, the MS may remain tuned to the        cellular network to send Paging Response and accept the call.        After the voice call, the MS may tune to the WLAN to continue        the packet data session (if the MS still has WLAN coverage).    -   2. Upon receiving the page, the MS immediately tunes back to the        WLAN and sends a Disassociation message to the AP. Then, the MS        switches to the cellular network, sends a Paging Response, and        accepts the call. After the voice call, the MS may need to start        a new packet data session in either the cellular network or the        WLAN.

According to scenario (4), if the MS is tuned to the WLAN but detectsthe signal strength has dropped below an acceptable threshold, the MSmay tune to the cellular network and proceeds to handover the packetdata session to cellular network.

FIG. 10A illustrates one example of scenario (2), wherein the MS 702currently has a packet data session with the cell network 706. The MS702 scans for a WLAN instruction message from the cell network 706.Using the WLAN instruction message, which provisions the MS, the MSscans for WLAN coverage. Upon detection of the WLAN, the MS 702 notifiesthe cell network of the result. As illustrated, the MS 702 detects aWLAN (AP 704), and in response sends a notification to the cellularnetwork of the scan result. The cellular network may then instruct theMS 702 to switch to the WLAN. The decision to switch from the cellularnetwork 706 to the WLAN is based on loading of the network, bandwidth ofthe user, data requirements, etc. Once the cellular network 706instructs the MS 702 to switch, the cellular network 706 removes thedata session. The MS 702 then initiates authentication with the AP 704.Note that if the authentication fails the MS may need to re-establishwith the cellular network.

FIG. 10B illustrates another example of scenario (2), wherein the MS 702currently has a packet data session with the cell network 706. The MS702 scans for a WLAN instruction message from the cell network 706.Using the WLAN instruction message, which provisions the MS, the MSscans for WLAN coverage. Upon detection of the WLAN, the MS 702 notifiesthe cell network of the result. As illustrated, the MS 702 detects aWLAN (AP 704), and in response initiates authentication with the AP 704.The cellular network 706 then starts a timer, and when a time out periodis expired, the cellular network 706 removes the data session.

FIG. 10C illustrates still another example, wherein the MS 702 iscurrently has a packet data session with the cell network 706. The MS702 scans for a WLAN instruction message from the cell network 706.Using the WLAN instruction message, which provisions the MS, the MSscans for WLAN coverage. When no WLAN is detected, the MS 702 sends thesearch result to the cellular network 706. The MS 702 continues the datasession with the cellular network 706.

Two Tuners

In the following example, the Mobile Station (MS) has two tuners thatcan tune to a cellular frequency and the WLAN frequency simultaneously.A MS 300 is illustrated in FIG. 6 having an ESSID list 302, which isstored in memory, a first tuner, tuner A 304, and a second tuner, tunerB 306. Tuner A is configured for communication with a WLAN. Tuner B 306is configured for communication with a wireless cellular network. Asillustrated, when MS 300 is within range of accessing AP 320, tuner A304 scans for a WLAN beacon transmitted by AP 320. The WLAN beacon istransmitted periodically and identifies the WLAN supported by AP 320.Tuner B 306 scans for a paging indicator from the cellular networktransmitted by Base station Transceiver System (BTS) 322. In this way,the MS 300 may scan for WLAN coverage while also scanning for cellularpages. Thus, the MS 300 detects WLAN coverage and performs systemselection between WLAN and the cellular system using one tuner for eachaccess medium.

The MS 300 may implement any of a variety the physical configurations.For example, a “Type A” device is a single handheld device (e.g., phone,Personal Digital Assistant (PDA)) having a built-in WLAN tuner and acellular network tuner, or a slotted-in WLAN tuner card and cellulartuner card (e.g., CDMA2000 card). Additionally, a “Type B” device is alaptop computing device, such as a personal computer, having a WLANtuner card, wherein the laptop computing device is connected to acellular handset, such as a handset supporting cdma2000 communications.

For a type A device, the MS 300 is a single physical device (e.g.,handset, PDA) that supports both WLAN and cellular network protocols.The MS 300 has two Radio Frequency (RF) tuners: a first for the cellularnetwork; and a second for the WLAN.

Returning to FIG. 6, note that the WLAN beacon and the page indicatorare not necessarily transmitted at a same time or with a same period.The MS 300 scans for the WLAN beacon with tuner A 304 over a cyclehaving a first period. The MS 300 scans for the page indicator of thecellular network over a cycle having a second period. Typically thesecond period is shorter than the first period. In other words, the pageindicators are generated more frequently than the WLAN beacons.

Power conservation is an important design criterion in system detectionand selection. Conservation of power at the mobile device is highlydesirable to extend the operational time of the device betweenrecharging the battery. If the MS 300 decides to scan for WLAN coverage,it is desirable to minimize power consumption during such scan whilestill monitoring cellular paging.

The MS 300 may decide to scan for WLAN coverage based on one or morefactors, e.g., user command(s), pre-configured preference(s),application status (e.g., on-going packet data session), WLANavailability advertisement as received from the cellular network, etc.One WLAN protocol defined by IEEE 802.11, and referred to herein as“802.11,” allows the MS 300 to scan for WLAN coverage passively oractively. In passive scanning, the MS 300 listens for the WLAN beaconsent by the AP 320 on WLAN frequencies. The WLAN beacon contains theESSID of AP 320, referred to as ESSID (AP 320). If the ESSID(AP 320)matches an ESSID stored in the MS 300 ESID list 302, this is anindication that the MS 300 has detected WLAN coverage, and that suchcoverage is provided by the MS 300 service provider. In active scanning,the MS 300 transmits a Probe Request that contains the ESSID of the MS300. If the AP 320 receives the Probe Request and the ESSID of the MS300 matches the ESSID of the AP 320, the AP 320 transmits a ProbeResponse to the MS 300. If the MS has a list of multiple ESSIDs, the MSmay transmit a Probe Request containing an ESSID having the highestpreference. The ESSID preference may be stored as a system selectionparameter in the Preference Database (described hereinabove).

For conserving power, it is desirable to maximize a sleep mode for MS300. In other words, it is desirable to maximize the time when MS 300 isusing reduced power, or is in a sleep mode. Additionally, and as aresult of such maximization, it is desirable to minimize the MSawake-time, or full power operation. Therefore, when the MS 300periodically wakes, such as to check for pages or WLAN beacons, the MS300 should simultaneously scan for any WLAN beacon as well as monitorfor a cellular page indicator. If the paging cycle and beacon cycle arenot synchronous, then the MS 300 wakes up according to the paging cycleto monitor the paging Indicator. In this scenario, when the MS 300wakes, the MS 300 uses active scanning to scan for the WLAN beacon. Ifthe paging cycle and beacon cycle are synchronous, then the MS wakes upperiodically to monitor the paging Indicator and passively listen forany WLAN beacon. Synchronous paging and beacon cycles provide a morepower-efficient operation due to the use of passive scanning; however,such synchronization requires the AP 320 clock be synchronized with thecellular network timing.

One method for synchronization of the paging cycle and WLAN beacon cycleis to schedule the WLAN beacon to arrive at the same time as the firstpaging indicator in the Quick Paging Channel. According to this method,each MS is scheduled to wake just before the scheduled WLAN beaconarrival time. Note that due to potential collisions, the WLAN beacon maynot be sent at the scheduled time; thus, there is no guarantee that agiven WLAN beacon will arrive at the scheduled or anticipated time. TheWLAN beacon is transmitted as a frame of data and therefore, complieswith the same rules for accessing the shared medium as othertransmissions. After receiving the WLAN beacon, some MS may need to stayawake a little longer in order to scan for the paging indicator. Again,this method requires synchronization of the clocks for generating theWLAN beacon and the cellular network paging indicator. Suchsynchronization is not always feasible or available.

After the MS 300 detects WLAN coverage, receives the WLAN beacon, the MS300 uses certain criteria to handover a packet data session from thecellular network to the WLAN. The criteria may include whether the MS isidle in cellular network (i.e., no dedicated channel) or whether theWLAN signal strength is stable, etc. The MS 300 may wait for a pendingpacket data session to go dormant in the cellular network. The MS 300 dthen performs packet data session handover (i.e., sending Mobile IPregistration via WLAN). This may be useful to minimize serviceinterruption. Similarly, the MS 300 may perform packet data sessionhandover when the WLAN signal strength is above an acceptable thresholdfor a specified period of time. In this way, the MS 300 ensures thataccess to the WLAN is sustainable. The measure may be any measure ofchannel quality and/or signal strength. The threshold may bepredetermined or may dynamically be adjusted based on the actualperformance of the communication. This may be useful to avoiding anyping-pong effect whereby the MS 300 switches between WLAN access andcellular network access due to changing conditions or signal strengththat is at the margin of tolerance for operation. Still further, upondetection of the WLAN, the MS 300 may notify the user and wait for theuser to manually select WLAN.

Another consideration is to minimize power consumption while the MS 300is receiving data via the WLAN and is monitoring for cellular paging.After the MS 300 performs the handover of the packet data session to theWLAN, the MS 300 may receive data via the WLAN as well as incomingcircuit-switched voice calls via the cellular network. The MS 300 relieson the cellular sleep mode to conserve power while monitoring forcellular paging. The 802.11 protocol has a similar method for the MS 300to conserve power while waiting for incoming data. If the cdma2000 QuickPaging Channel, or other similar mechanism, is supported, the MS 300 mayfurther conserve power by synchronizing the cellular sleep mode and the802.11 power-saving mode.

According to the 802.11 power-saving mode the MS 300 sends anAssociation Request (AR) to the AP 320, wherein the AR indicates anumber (e.g., N) of beacon periods that the MS 300 is to be in the powersaving mode. The AP 320 keeps track a list of MSs that have enabled thepower saving mode. The AP 320 buffers frames destined for the MS 300while it is in the power saving mode. The AP 320 periodically sends abeacon containing the Traffic Indication Map (TIM) (not shown)indicating whether each MS has frames buffered in the AP 320. The MS 300wakes up every N beacon periods to monitor the beacon and the includedTIM. If the TIM indicates pending frames for the MS 300, the MS 300sends a Power-Save Poll to the AP 320, to which the AP 320 responds bysending one frame of data to the MS 300. The frame will include acontrol field, wherein a control bit indicates if there are more framesbuffered for the MS 300. If the control bit is set, the MS 300 isrequired to send another Power-Save Poll to the AP 320. If the controlbit is cleared, there are no pending frames for MS 300.

The MS 300 may achieve further power conservation when the 802.11power-saving mode is synchronized with the cellular sleep mode. In thisway, the MS wakes up periodically to monitor for both beacon (andincluded TIM) as well as to monitor for the cellular page indicator.Synchronization may be achieved by synchronizing the clock of the AP 320to the cellular timing, wherein the cellular paging interval and WLANbeacon interval are in lock-step. For example, when the WLAN beaconinterval is equal to the cellular paging interval, the beacon may bescheduled to arrive at the same time as the first paging indicator inthe cellular system, such as provided on the cdma2000 Quick PagingChannel. Each MS wakes up just before the beacon arrival. Some MS mayneed to stay a little longer (e.g., 40 ms after WLAN beacon arrival) toreceive the paging indicator.

For systems such as those without the cdma2000 Quick Paging Channel, theBeacon cycle and paging cycle generally are not synchronous, i.e., thetime difference between the WLAN beacon and the cellular paging slot mayvary for each MS. If the time difference is small, then the MS can wakeup to monitor both the Beacon and its paging slot before goes back tosleep. If the time difference is large, such procedure may not bepower-efficient for each MS to wake up and stay awake to monitor boththe WLAN beacon and the paging slot. Note that each MS may have adesignated paging slot, and therefore, the differential time required toreceive both the WLAN beacon and the paging indicator may not be thesame for each MS and typically will be different.

FIG. 7 illustrates a process 350 applicable to the MS 300. The MS 300first wakes for a cellular paging indicator (step 354). The MS 300 mayschedule this waking to coincide with a common time for a first pagingindicator slot and a WLAN beacon, or may use some other criteria todetermine when to wake. The MS 300 determines (decision diamond 356)whether to perform active WLAN scanning or passive WLAN scanning. Foractive scanning, the MS 300 sends a request for a WLAN beacon (step358), and continues to then scan for the WLAN beacon (step 360). In thisway, the MS 300 avoid extended power consumption while for waiting for anext scheduled WLAN beacon transmission. For passive scanning, the MSscans for the WLAN beacon (step 360) until a beacon is detected.

FIG. 8 illustrates communication flow within a network 500 includingboth cellular communications and Internet Protocol (IP) communications.The Internet 502 is coupled to a Home Agent (HA) 516 associated with MS508. The Internet is further coupled to a File Transfer Protocol (FTP)server 514, an Access Router 510, and a Packet Data Service Node (PDSN)504. The Access Router 510 communicates with an AP 512 via a wirelessinterface. The interface between the Access Router 510 and the AP 512 isa WLAN interface, wherein the Access Router 510 and the AP 512 are partof a WLAN. When the MS 508 is situated so as to communicate with the AP512, the MS 508 accesses the WLAN via a wireless interface with the AP512. For cellular communications, the MS 508 communicates over the airwith a BS 506. The BS 506 is configured for communication with PDSN 504via an interface identified as cdma2000. Such interface may beconsistent with another cellular protocol.

Note that a wireless device may include multiple tuners, wherein eachtuner is adapted for communication with a different access medium, e.g.,WLAN and cellular network. Alternately, a wireless device may be coupledto another wireless device, wherein each includes a tuner, and thecombination results in multiple tuners. In one such configuration, alaptop (computing device) operates together with a cellular handset. Thelaptop includes a WLAN card or built-in WLAN port, while the handsetsupports cellular communications. WLAN information (e.g., ESSID) isprovisioned in the laptop to scan for WLAN coverage.

FIG. 9 illustrates signal and message flow in such a configuration. Asillustrated, the laptop 600 is coupled to the MS 602 for communication.The laptop 600 has a tuner, which is currently adapted for communicationwith a WLAN, such as via AP 604. The MS 602 has a tuner, which iscurrently adapted for communication with a cellular network 606, such asa cdma2000 network.

In the configuration illustrated in FIG. 9, the laptop 600 is currentlyprocessing a packet data session with the cellular network 606 throughthe MS 602. During the packet data session, when the MS 602 receives aWLAN availability advertisement from the cellular network 606, the MS602 may notify the laptop 600 via a signaling protocol defined betweenthe MS 602 and the laptop 600. On receipt of such notification thelaptop 600 may choose to scan for WLAN coverage. The laptop 600 may thenperform system selection based on WLAN signal strength and acquire aWLAN signal from AP 604. The laptop 600 and the AP 604 then authenticatethe connection. Once authentication is completed, the laptop 600disconnects from the cellular network through the MS 602. The MS 602then disconnects the packet data session with the cellular network 606.From this point, the packet data session is processed between the laptop600 and the AP 604.

As detailed in the example given above and with respect to FIG. 9, whenthe laptop 600 has a current packet data session with the cellularnetwork 606, the laptop may detect a strong WLAN signal through theresident tuner. The laptop 600 may choose to switch to WLAN accessimmediately. Upon WLAN detection, the laptop 600 needs to beauthenticated for WLAN access. For single subscription/authentication ofWLAN and cdma2000, the secret is stored in the handset's User InterfaceModule (UIM) (not shown), which may be removable or non-removable. Thus,signaling messages are needed between the laptop 600 and MS 602 toperform WLAN access authentication. If the WLAN access authentication issuccessful, the laptop 600 performs Mobile IP registration via the WLAN(i.e., via AP 604). If the Mobile IP registration is successful, thelaptop 600 sends a message (e.g., AT command) to the MS 602 to releasethe packet data session. The MS 602 may identify the data session by aService Option (SO), such as SO 33 in cdma2000. The laptop 600 may thenmaintain the packet data session via the cellular network until handoverof the packet data session to the WLAN is completed.

Alternatively, the laptop may switch to the WLAN if the packet datasession currently has no data pending transfer so as to minimize serviceinterruption (e.g., downloading a file). Upon detecting a strong WLANsignal, the laptop 600 waits for a given time period (e.g., severalseconds) to detect any activity of data transfer. If no activity isdetected, the laptop 600 performs WLAN access authentication, followedby Mobile IP registration via the WLAN, and finally release of thecellular packet data service option, as described above.

When the laptop 600 is accessing WLAN and the signal strengthdeteriorates below an acceptable threshold, the laptop 600 may triggerthe MS 602 to originate a packet data service option. The trigger may bean explicit signaling message (e.g., AT commands) or Mobile IPregistration message, etc. wherein the laptop 600 desires to send viathe cellular network. If the Mobile IP registration is successful, thelaptop 600 continues the packet data session via the cellular network.In order to avoid ping-pong effect between WLAN and the cellularnetwork, hysteresis mechanisms may be used, such as, switching to theWLAN only when the WLAN signal remains above a specified threshold for aspecified period of time. The laptop may switch between the WLAN and thecellular network automatically (e.g., operation transparent to the user)or manually initiated by the user.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the embodiments disclosed herein may be implemented aselectronic hardware, computer software, or combinations of both. Toclearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

1. In a wireless communication system, a method for identifying aWireless Local Area Network comprising: identifying WLAN availabilitycomprising identifying at least one available WLAN by an ExtendedService Set Identifier (ESSID) from a list comprising at least oneESSID; and broadcasting a WLAN advertisement via a common communicationchannel of the wireless communication system, wherein the WLANadvertisement includes the ESSID of the at least one available WLAN,wherein the wireless communication system is different from the at leastone available WLAN, and wherein the broadcasting via the commoncommunication channel enables multiple remote stations to access theWLAN advertisement.
 2. The method as in claim 1, wherein broadcastingthe WLAN advertisement comprises periodically broadcasting the WLANadvertisement.
 3. The method as in claim 1, wherein the WLANadvertisement is an overhead signaling message.
 4. The method as inclaim 1, further comprising: receiving a registration message from aremote station, wherein the registration message indicates WLANcapability for the remote station; and initiating the broadcasting ofthe WLAN advertisement in response to the registration message.
 5. Themethod as in claim 4, wherein the initiating of the broadcasting isbased on identifying a WLAN capability identifier in the registrationmessage.
 6. The method as in claim 1, wherein broadcasting the WLANadvertisement comprises broadcasting the WLAN advertisement for apredetermined time period.
 7. The method as in claim 1, whereinidentifying WLAN availability further comprises identifying by a basetransceiver station the at least one available WLAN having coverage in acell sector of the base transceiver station, wherein the list comprisingthe at least one ESSID corresponds to an operator of the wirelesscommunication system, and wherein broadcasting the WLAN advertisementfurther comprises broadcasting within the cell sector.
 8. The method asin claim 1, wherein identifying the available WLAN further comprisesidentifying the at least one WLAN having a roaming agreement with thewireless communication system.
 9. The method as in claim 1, whereinbroadcasting the WLAN advertisement further comprises including positioninformation for an Access Point (AP) supporting the at least oneavailable WLAN.
 10. A method for a remote station, comprising: receivinga Wireless Local Area Network (WLAN) advertisement via a commoncommunication channel of a wireless communication system, wherein theWLAN advertisement comprises a list of at least one Extended Service SetIdentifier (ESSID) corresponding to at least one available WLAN, whereinthe wireless communication system is different from the at least oneavailable WLAN; and scanning for the at least one available WLAN inresponse to the WLAN advertisement.
 11. The method as in claim 10,further comprising: automatically enabling a WLAN scan in response toreceiving the WLAN advertisement.
 12. The method as in claim 10, whereinreceiving the WLAN advertisement comprises: receiving a WLANadvertisement including position information for an Access Point (AP)supporting the at least one available WLAN; comparing the positioninformation to a current location of the remote station; and if thecurrent location of the remote station is proximate the AP, scanning forthe at least one available WLAN.
 13. The method as in claim 12, whereinthe position information includes the latitude and longitude of the AP.14. The method as in claim 12, further comprising: displaying theposition information for the AP on the remote station.
 15. The method asin claim 14, further comprising: initiating a WLAN scan in response todisplaying the position information.
 16. The method as in claim 10,wherein receiving the WLAN advertisement further comprises one ofreceiving periodically or receiving over a predetermined period of time.17. The method as in claim 10, further comprising transmitting aregistration message to the wireless communications system, wherein theregistration message comprises a WLAN capability for the remote station,and wherein receiving the WLAN advertisement further comprises receivingin response to the registration message.
 18. The method as in claim 10,wherein receiving the WLAN advertisement further comprises receivingfrom a base transceiver station the at least one available WLAN havingcoverage in a cell sector of the base transceiver station, wherein thelist comprising the at least one ESSID corresponds to an operator of thewireless communication system, and wherein receiving the WLANadvertisement further comprises receiving within the cell sector. 19.The method as in claim 10, wherein receiving the WLAN advertisementfurther comprises identifying the at least one WLAN having a roamingagreement with the wireless communication system.
 20. In a wirelesscommunication system, an apparatus for identifying a Wireless Local AreaNetwork comprising: means for identifying WLAN availability comprisingmeans for identifying at least one available WLAN by an Extended ServiceSet Identifier (ESSID) from a list comprising at least one ESSID; andmeans for broadcasting a WLAN advertisement via a common communicationchannel of the wireless communication system, wherein the WLANadvertisement includes the ESSID of the at least one available WLAN,wherein the wireless communication system is different from the at leastone available WLAN, and wherein the broadcasting via the commoncommunication channel enables multiple remote stations to access theWLAN advertisement.
 21. An apparatus for a remote station, comprising:means for receiving a Wireless Local Area Network (WLAN) advertisementvia a common communication channel of a wireless communication system,wherein the WLAN advertisement comprises a list of at least one ExtendedService Set Identifier (ESSID) corresponding to at least one availableWLAN, wherein the wireless communication system is different from the atleast one available WLAN; and means for scanning for the at least oneavailable WLAN in response to the WLAN advertisement.
 22. In a wirelesscommunication system, an apparatus comprising: memory storage deviceadapted to store computer readable instructions for identifying aWireless Local Area Network (WLAN); and processing unit coupled to thememory storage device, adapted to: identify WLAN availability comprisingidentifying at least one available WLAN by an Extended Service SetIdentifier (ESSID) from a list comprising at least one ESSID; andbroadcast a WLAN advertisement via a common communication channel of thewireless communication system, wherein the WLAN advertisement includesthe ESSID of the at least one available WLAN, wherein the wirelesscommunication system is different from the at least one available WLAN,and wherein the broadcast via the common communication channel enablesmultiple remote stations to access the WLAN advertisement.
 23. Theapparatus as in claim 22, wherein the processing unit is further adaptedto periodically broadcast the WLAN advertisement.
 24. The apparatus asin claim 22, wherein the WLAN advertisement is an overhead signalingmessage.
 25. The apparatus as in claim 22, wherein the processing unitis further adapted to: receive a registration message from a remotestation, wherein the registration message indicates WLAN capability forthe remote station; and initiate the broadcast of the WLAN advertisementin response to the registration message.
 26. The apparatus as in claim25, wherein the processing unit is further adapted to initiate thebroadcast of the WLAN advertisement further based on identifying a WLANcapability identifier in the registration message.
 27. The apparatus asin claim 22, wherein the apparatus comprises a base transceiver station,wherein the at least one available WLAN has coverage in a cell sector ofthe base transceiver station, wherein the list comprising the at leastone ESSID corresponds to an operator of the wireless communicationsystem, and wherein the processing unit is further adapted to broadcastthe WLAN advertisement within the cell sector.
 28. The apparatus as inclaim 22, wherein the WLAN advertisement further comprises anidentification of the at least one available WLAN having a roamingagreement with the wireless communication system.
 29. An apparatus for aremote station, comprising: memory storage device adapted to storecomputer readable instructions for identifying a Wireless Local AreaNetwork (WLAN); and processing unit coupled to the memory storagedevice, adapted to: receive a advertisement via a common communicationchannel of a wireless communication system, wherein the WLANadvertisement comprises a list of at least one Extended Service SetIdentifier (ESSID) corresponding to at least one available WLAN, whereinthe wireless communication system is different from the at least oneavailable WLAN; and scan for the at least one available WLAN in responseto the WLAN advertisement.
 30. The apparatus as in claim 29, wherein theprocessing unit is further adapted to automatically enable a WLAN scanin response to receiving the WLAN advertisement.
 31. The apparatus as inclaim 29, wherein the WLAN advertisement further comprises positioninformation for an Access Point (AP) supporting the at least oneavailable WLAN, and wherein the processing unit is further adapted tocompare the position information to a current location of the remotestation and, if the current location of the remote station is proximatethe AP, scan for the at least one available WLAN.
 32. The apparatus asin claim 29, wherein the processing unit is further adapted to displaythe position information for the AP on the remote station and toinitiate a WLAN scan in response to displaying the position information.33. The apparatus as in claim 29, wherein the processing unit is furtheradapted to periodically receive the WLAN advertisement or receive theWLAN advertisement over a predetermined period of time.
 34. Theapparatus as in claim 29, wherein the processing unit is further adaptedto transmit a registration message to the wireless communicationssystem, wherein the registration message comprises a WLAN capability forthe remote station, and wherein the processing unit is further adaptedto receive the WLAN advertisement in response to the registrationmessage.
 35. The apparatus as in claim 29, wherein the processing unitis further adapted to receive the WLAN advertisement from a basetransceiver station, wherein the at least one available WLAN hascoverage in a cell sector of the base transceiver station, wherein thelist comprising the at least one ESSID corresponds to an operator of thewireless communication system, and wherein the processing unit isfurther adapted to receive the WLAN advertisement within the cellsector.
 36. The apparatus as in claim 29, wherein the WLAN advertisementfurther comprises an identification of the at least one available WLANhaving a roaming agreement with the wireless communication system. 37.At least one processor configured to identify a Wireless Local AreaNetwork in a wireless communication system, comprising: a first modulefor identifying WLAN availability comprising identifying at least oneavailable WLAN by an Extended Service Set Identifier (ESSID) from a listcomprising at least one ESSID; and a second module for broadcasting aWLAN advertisement via a common communication channel of the wirelesscommunication system, wherein the WLAN advertisement includes the ESSIDof the at least one available WLAN, wherein the wireless communicationsystem is different from the at least one available WLAN, and whereinthe broadcasting via the common communication channel enables multipleremote stations to access the WLAN advertisement.
 38. A productconfigured to identify a Wireless Local Area Network in a wirelesscommunication system, comprising: a computer-readable medium stored in astorage medium, comprising: at least one instruction operable to cause acomputer to identify WLAN availability comprising identifying at leastone available WLAN by an Extended Service Set Identifier (ESSID) from alist comprising at least one ESSID; and at least one instructionoperable to cause the computer to broadcast a WLAN advertisement via acommon communication channel of the wireless communication system,wherein the WLAN advertisement includes the ESSID of the at least oneavailable WLAN, wherein the wireless communication system is differentfrom the at least one available WLAN, and wherein the broadcasting viathe common communication channel enables multiple remote stations toaccess the WLAN advertisement.
 39. At least one processor configured fora remote station, comprising: a first module for receiving a WirelessLocal Area Network (WLAN) advertisement via a common communicationchannel of a wireless communication system, wherein the WLANadvertisement comprises a list of at least one Extended Service SetIdentifier (ESSID) corresponding to at least one available WLAN, whereinthe wireless communication system is different from the at least oneavailable WLAN; and a second module for scanning for the at least oneavailable WLAN in response to the WLAN advertisement.
 40. A productconfigured for a remote station, comprising: a computer-readable mediumstored in a storage medium, comprising: at least one instructionoperable to cause a computer to receive a Wireless Local Area Network(WLAN) advertisement via a common communication channel of a wirelesscommunication system, wherein the WLAN advertisement comprises a list ofat least one Extended Service Set Identifier (ESSID) corresponding to atleast one available WLAN, wherein the wireless communication system isdifferent from the at least one available WLAN; and at least oneinstruction operable to cause the computer to scan for the at least oneavailable WLAN in response to the WLAN advertisement.